VEGFA and colorectal cancer: Bevacizumab is a monoclonal antibody with a long half-life estimated at 20 days, and thus an expectation for an extended duration of action.25 As an example, following intraocular administration, bevacizumab was associated with complete intravitreal VEGF blockade for a minimum of 4 weeks.34 In a study of colorectal cancer patients undergoing surgery, bevacizumab was found to be active and block circulating VEGF 6 weeks after cessation.22 Although this may provide some justification for prolonged bevacizumab washout periods, measurement of plasma VEGF may be insufficient in this regard.